Process for sealing mains



w. E. ROSENGARTEN, JR, ET AL 3,265,782

Aug. 9, 1966 PROCESS FOR SEALING MAINS Original Filed May '7, 1962 4Sheets-Sheet 1 w m 9% r W p 1 2 y L f Z w M m g- 1966 I w. E.ROSENGARTEN, JR, ETAL 3,265,782

, PROCESS FOR SEALING MAINS 4 Sheets-Sheet z 1 9, 1966 w. E.ROSENGARTEN, JR, ETAL 3,265,782

PROCESS FOR SEALING MAINS Original Filed May 7, 1962 4 Sheets-Sheet 4.

w V Z a m e/ a a i K M W ATTORNEYS United States Patent 3,265,782PROCESS FOR SEALING MAINS Walter E. Rosengarten, Jr., 2895 GradyvilleRoad, Broomall, Pa., and Archibald T. Flower, Gleuside, and David L.Buchanan, Flourtown, Pa.; said Flower and gait! Buchanan assignors tosaid Rosengarten, Broomall,

a. i D al application May 7, 1962, Ser. No. 192,817, now Patent No.3,178,793, dated Apr. 20, 1965. Divided and this application Jan. 25,1965, Ser. No. 427,638 Claims. (Cl. 264-32) The present invention is adivision of our co-pending application Serial No. 192,817, filed on May7, 1962, for Process and Apparatus for Sealing Mains.

The present invention relates to a process for sealing mains andparticularly to a process for sealing bell and spigot joints in existingmains carrying fluids such as fuel gas, water and other liquids.

An object of this invention is to provide a method for sealing gas mainsatthe joints by applying a mold there to from a position remote to themain.

It is a further purpose to provide a method for sealing gas mains whichpermits a substantial reduction in the size of the excavation requiredand in the area of the pavement which must be destroyed in order to gainaccess to the main.

A further object of this invention is to provide a method for sealinggas mains which keeps the main in service while it is being sealed.

Additionally it is an object of this invention to seal gas mains bysurrounding the main with a flexible mold on an articulated frametightening the mold against the joint and subsequently introducingsealing material into the mold.

A still further object of the invention is to provide a method forsealing joints which permits the restoration of trafiic conditionsduring non-working hours by keeping the mold mechanism below the surfacelevel during setting or curing and by applying a cover over the top ofthe hole.

A further object of this invention is to seal a pipe joint in a main byapplying a reusable mold to the joint, introducing sealing material intothe mold to seal the joint and subsequently removing the mold andapplying it to another jointto be sealed.

A further purpose is to provide a method for cleaning the joint prior toattaching the mold.

The drawings illustrate by way of example one embodiment of a sealingdevice and one embodiment of a cleaning device which may be used in thesealing of gas main joints according to theobjects of this invention.

FIGURE 1 is an axial elevation of the cleaning device of the inventionabout to be inserted on a main.

FIGURE 2 is a section taken on the line 2-2 of FIG- URE l. 1

FIGURE 3 is an enlarged sectional view taken on the line 3-3 of FIGURE1.

FIGURE 4 is an enlarged partial sectional elevation of the frame andnozzle of the cleaning device of the invention.

FIGURE 5 is an axial elevation of the cleaning deviceof the inventionapplied to the top side of a main.

FIGURE 6 is an axial elevation of the cleaning device of the inventionshowing the nozzle at the underside of the pipe.

FIGURE 7 is a section taken on the line 77 of FIG- URE 5.

FIGURE 8 is a transverse section through the pipe,

- showing the mold of the invention being applied to a main at a belland spigot joint.

FIGURE 9 is a partial axial elevation of the mold de- 3,265,782 PatentedAugust 9, 1966 vice of the invention in place on a main for molding.

FIGURE 10 is an enlarged section taken on the line 10-10 of FIGURE 9.

FIGURE 11 is a fragmentary plan view of the mold of the invention.

FIGURE 12 is a section taken on the line 1212 of FIGURE 11.-

FIGURE 13 is a section taken on the line 1313 of FIGURE 8. Y

FIGURES 14 to 17 show the various steps in sealing a bell and spigotjoint using the present invention.

FIGURE 14 is a fragmentary longitudinal elevation showing the cleaningdevice of the invention being applied to the joint.

FIGURE 15 shows a vacuum cleaner to suck sand and loose earth out of thehole being applied to clean the joint.

FIGURE 16 shows the mold of the invention applied to the joint. I

FIGURE 17 shows the manner in which the mold may be left in the holewhile the sealing material is setting.

FIGURE 18 is an enlarged exploded sectional perspective of a mold andarticulated frame.

FIGURE 19 is enlarged fragmentary side elevation showing the clamp andthe related handle.

FIGURE 20 is a top view of the clamp and related handle shown in FIGURE19, with the handle in section.

Describing in illustration but not in limitation and referring to thedrawings:

In the distribution of gas for domestic, commercial, and industrial use,a network of mains is employed to carry the gas from central points topoints of usage. These mains in many instances have bell and spigotjoints which are typically packed by jute and then usually leaded orcemented at the outside. When these joints were originally installed,many of the mains were distributing carbureted water gas or coke ovengas which contained a substantial content of moisture, tars and oils.These liquids had over a period of time, saturated the packing materialsto provide relatively leak-free joints.

' In recent years, there has been a shift over to natural gas which isof a comparatively d-ry nature. The natural gas has reduced byabsorption the content of tars and oils which has been built up in thejoints, and thus drying out the joints. Furthermore, many of the textilepacking materials tend to shrink when they dry. The result encounteredin a widespread way has been a tendency of the packing to shrink,causing openings through the dried-out packing which permit leakage ofgas.

In other instances, leaks have. been caused in many areas of the countryby active earth conditions which in certain localized areas has involvedsettling ormovement of the earth in the order of half inch or even oneinch a year. This settling has caused a certain tendency formisalignment of the various pipe section-s, both vertically and alsohorizontally, and this has further increased the.

' tendency toward leakage. This misalignment in some instances hascaused a withdrawal to some extent of the pipe from the spigot causingadditional leakage.

All of these factors have made it quite important to develop sometechnique for sealing the joints. One approach to the problem has beento cut out the line, and actually introduce a self-propelled crawlerwhich both cleans the line and locates the joint, sometimeselectronically, and then to coat the inside with a suitable sealingwhich may be used without taking the line out of service.

These usually involved digging an excavation at each joint large enoughfor a man to descend to the area around the hell or pipe and to fix abolted clamp fitting around the joint. The fitting compresses a rubbergasket which seals against the outside of the bell and also against theadjoining straight pipe section of the spigot.

There is also another technique which in effect butters epoxy resinaround the face of the bell in order to accomplish sealing. This methodalso requires extensive excavation.

The present invention permits the line to remain in service at normal(superatmospheric) pressure without any interruption of gas flow and canbe carried on with a minimum of excavation. The process and equipmentcan function using a slit about 18 inches in length and about 4 inchesin width where it penetrates the sidewalk or other paving, and slightlywider in the earth at the bottom where the pipe joint is located.

The present invention as compared to any preformed gasket techniquegives greatly improved seal by providing a bond to the metal surface.

Principally due to the reduced amount of excavation, the speed of theoperation is considerably increased compared 'to the other techniques.It is believed that the time is not more than one-half that of the bestprior technique.

By virtue of the relatively very small size of the opening in the pavingit is much less costly to rcpave after sealing the leak than it was inprior art methods. In addition high-way authorities have permittedopenings of this size in paving to be repaired with a mere block ofconcrete, rather than expensive cutback and repaving according tospecifications. This provides quite substantial savings. Also, it isusually possible to work around reenforcing rods in concrete paving,thus eliminating the necessity for replacing and/or tie welding new rodswhen repaving.

In accordance wtih the present invention, a suitable cleaning techniqueis employed which may conveniently be sand-blasting but could begrit-blasting, wheat blasting or refractory blasting. Alternatively, thejoint could be cleaned by wire brushing, scraping or by solvent. Afterthe cleaning has been completed a mold is introduced about the jointmore or less by remote control since the operator is at ground level. Asuitable sealing material is introduced under pressure into the moldspace.

Considering now the invention in detail, the preferred sand-blastingdevice is shown in FIGURES 1 to 7, inclusive. A handle 20 is pivotallyconnected at 21 to frame 22 having arcuate elements 23 and 24 suitablypivoted at 25. A connector element 26 supports elements 23 and 24 topivot and also supports pivot 27 to which handle 20 is attached at 21.Handle 20 has a suitable U-shaped bend 28 at the end adjacent frame 22.Rollers '30 are pivotally mounted on arcuate elements 23 and 24 whichengage circumferentially on the pipe 116. As best seen in FIGURE 7,there are two rollers 30 on the outer end of element 23 and one rollernear the pivot and one roller on the outer end of element 24, therollers being disposed at approximately 120 intervals around thecircumferonce. A nut and bolt 31 retains helical compression spring 32which biases the segments 23 and 24 together as best seen in FIGURE 4.

A nozzle 33 having orifice opening 34 is held to arcuate element 24 byextension 35 and retainer 36. Retainer 36 is held against extension 35by nuts and bolts 37 which are spring loaded by helical compressionsprings 38 to secure the nozzle 33 by engaging surface 40 of the nozzle.A shoulder 41 and nut 42 threaded on nozzle 33 prevent longitudinalmovement of the nozzle with respect to the arcuate element 24. Thespring loaded yieldable retainer 36 allows the nozzle 33 to be rotatedselectively.

A hose 43 is connected to the nozzle at 44 whereby sand or otherabrasive can be brought to the nozzle and into contact with the pipe,the hose being connected at the outer end to any suitable air compressorand abrasive pickup mechanism as well known.

Considering now the mold, frame, and handle of the invention as bestseen in FIGURE 8, a mold suitably of any flexible resilient materialsuch as rubber or the like, has a radial separation 51. The mold shapeconforms circumferentially to a pipe circumference for covering a belland spigot joint and leaves suitable interior space for sealing materialto be introduced. The mold in longitudinal section, as best seen inFIGURES l0 and 18, comprises a flange section 52 of an innercircumference conforming in a closed position to the circumference ofthe spigot 53. A radially extending web 54 extends for a suitabledistance, and has at its radially outward extremity a longitudinallyextending flange 55 whose inner face 56 conforms circumferentially tothe outer face of the bell 57. An integral circumferential extension 58extends circumferentially around flange portion 55.

Two circumferentially spaced radially extending openings 61 and 62extend through the mold. At the inner face of the mold 50 a bevel face64 extends from the spigot to the bell when the mold is in closedposition during the scaling of a joint. Thus, there is created acircumferentially extending mold cavity 65 about the bell and spigotjoint. This mold cavity 65 extends longitudinally adjacent existing leadpacking 66 and jute packing 67. In some cases cement has been usedinstead of lead.

Extending circumferentially around and radially outward from flexiblemold 50 is an articulated circumferentially segmented frame 68. Frame 68is composed of a plurality of longitudinally segmented segments 70 and71 which are held in radial relation to one another in a circle and inabutting relationship to mold 50 by a leaf spring 70' which passescircumferentially around the outside of the mold 50 and passes over aseries of bolts 71 which longitudinally loosely join segments 70 and 71.

It should be understood that while the action of one pair of segments isdescribed, these segments extend around the complete circumference ofthe mold as at 72.

As shown in FIGURE 18, segment 70 has a portion 74 which rests againstthe flange 52 of mold 50, a web 75 which extends radially outward andhas extending at right angles a portion 76 with a bearing surface whichcircumferentially rests against mold 50. A radially outwardly extendingportion 77 has at its radially outer end lateral extensions 78 adjacentits circumferential ends which engage with notched portions on matinglongitudinal segment 71.

Mating longitudinal segment 71 has a radially extending flange 80 whichconforms to the longitudinal extension 55 of mold 50. A circumferentialportion 81 fits against the mold at its outer circumference and has aradially extended portion 82 whose inward surface has circumferentialnotches 83 at its radially outer end for engagement with the extensions78. It should be noted that the notches form fulcrums for the pointedextensions 78 on the mating longitudinal segment 70 which act to formpivots for the longitudinal segments. This serves to articulate the moldframe both radially and longitudinally, so that the mold will alwaysclose against the outside of the spigot and against the outside of thehell even though one or the other may lack perfect concentricity or mayvary somewhat in diameter.

The portions 77 and 82 of the respective segments 70 and 71 carrylongitudinally inward circumferential extensions 84 disposed adjacenttheir radial inner ends. The longitudinal sections of the frame 70 and71 are held together in position by the bolt 71' which passes through alongitudinal opening 79 centrally in the portion 77 of the segment 70and engages a threaded corresponding opening 79' in the portion 82 ofthe segment 71. The extension 58 of the mold 50 is engaged between theportions 77 and 82 in such manner that the extensions 84 engage theindent at 60 the radial inward portions of the lateral sides of theextension 58 and hold the mold 50 securely in the position as shown inFIGURE 10. The radial outward edge of the extension 58 has notches 59which engage the respective bolts 71 and properly position the severalsegments of frame 68 with respect to the mold 50.

Radially outward extensions 85 of the portions 76 and 81 havingcircumferential openings 86 receive flexible cables 87 which extendcircumferentially around the mold frame radially in'ward of the bolt 71and force the frame segments radially inward upon the application oftension to the cables. When the elements shown in FIGURE 18 areassembled as in FIGURES 8 to '12 inclusive, the spring 70' is disposedradially outward of the bolts 71' and radially inward of the extensions78.

A terminal segment 88 has attached thereto an arcuate guide 90 bybolting or other means. The guide 90 has a bevelled end portion 91 atone end and a handle 92 of suitable length and desirably of tubularconstruction which extends tangentially from the mold frame. This handlecan be suitably for instance of a length of seven feet so that it canconveniently be manipulated from above the ground. The handle isdesirably subdivided at 93 by telescoping or by any other suitablemeans. The handle has at its end away from the mold a tension mechanismwhich can suitably be of the conventional jack type as shown at 94. Thisjack mechanism 94 has a portion 95 extending longitudinally of handle 92and is, for instance, of rectangular cross section having spaced notches96.

A lever 97 has suitable fulcrum and engaging means not shown forengaging notches 96 whereby a mechanical advantage is secured so that atangential force applied in a direction away from the mold can besecured on a curved saddle 98 by the application of force on lever 97.The curved saddle 98 receives a loop integral with and formed fromcables 87.

Guides 100 lying in parallel planes transverse to the pipe axis extendcircumferentially from the side faces of the terminal segment 88. Theguides 100 act to guide terminal segment 101 into positionlongitudinally and the guide 91 acts to align segment 101 with segment88 circumferentially when force is applied to cable 87. When the mold 50is in closed position, as best seen in FIGURE 12, the mold 50 hasterminal faces 102 and 103 which come into abutting relationship andserve to form a closed mold which extends circumferentially continuouslyabout the bell and spigot joint.

A clamp 104 is fixed to theportion of the handle closest to the frame insuch manner that the cable 87 can be clamped by tightening bolt 105 sothat the force at the jack mechanism 94 may be released withoutreleasing the force exerted by the cable at the mold frame.

Clamp 104 is comprised of a channel element 121 bent into a right anglewith outwardly protruding flanges, having a longitudinal extension 122of a substantial part of the web of one leg 12-3' of the angle and anopening 124 in the web of the other leg 123. The wheel-handled bolt 105passes through the opening 124 and engages a threaded opening 125 in akeeper element 126, conveniently of a channel similar to element 121,which is provided with a slot 127 to receive and anchor the enlarged endof the extension 122, the latter beingspread at the end to preventseparation of the elements 121 and 126.

The handle 92 is provided with a transverse opening 128 offset from thediameter, to receive the bolt 105. The clamp 104 is applied to thehandle 92 so that the leg 123 is adjacent the side nearest the opening128. The clamp in the open position receives cables 87 in such mannerthat they are engaged between the jaws 123 and 126 of the clamp beyonddead center or inward of a diameter of the handle 92. When the clamp istightened, the cables are thus firmly grasped and tend to be forcedinwardly of the jaws toward the leg 123 rather than to be squeezed outtherefrom. I

Extending through the radially extending openings 61 and 62 is an inletorifice 107 and an outlet orifice 106 which can suitably be shortlengths of small diameter rigid tubing. Connected to the inlet orifice107 is flexible tubing 110 and connected to the outlet orifice 106 isflexible tubing 108. Fluid plastic is supplied through opening 111 oftube 110 and controlled by valve 114. Outlet tube 106 connects throughtube 108, through pressure indicating gauge 113 and through valve 112 tothe atmosphere.

The process of the invention can use any suitable curable sealingmaterial, although we have preferably used an epoxy resin of thecharacter described in the text, Epoxy Resins: Their Application andTechnology," published in 1957, by H. Lee and K. Neville.

It will be evident that in the preferred embodiment the sealing materialshould have several different properties which will cooperate to renderit most suitable for use in the present invention. The sealant shouldinitially be a liquid which can be injected into the mold under amoderate pressure. After the sealant has been injected and has filledthe mold, it should undergo a change of state within a reasonable timeand not excessive time. For good results the change should not takeplace until about fifteen minutes have elapsed so as to allow adequatetime for injection, and the change should take place within six-teenhours so that it will not be necessary to leave the mold in placeindefinitely. The material may cure or set either chemically, as bypolymerizing or cross linking, or other plastic curing mechanism, or itmay simply cool and solidify. The sealant should form a bond of adequatestrength to the suitably clean surface of the main. Thus, where the mainis of cast iron cleaned by sand-blasting, we have found that bondshaving an adhesive tensile strength of the order of 500 psi. can readilybe obtained by using the epoxy resins above referred to. The sealantshould of course be capable of releasing from the mold by a suitablemold release agent as well known.

The sealant in its final form should preferably remain flexible to asufiicient extent to absorb energy due to traflic passing overheadwithout failure. The sealant should also be resistant to chemicaldeterioration by contact-with the earth and the medium within the main,and therefore should not undergo softening, cracking, dissolving ordisintregation within its normal service life.

The sealant in its final form should have negligible cold flow at normaltemperatures and under the pressure to which it is normally subjected.

In operation, a 'hole 115 is dug from the street or pavement surface tothe level of the main 116. This hole can be suitably of a cross sectionof 4" x 18" at the surface and is then extended to any necessarydimension surrounding the pipe to introduce the mechanism for cleaningand sealing. After digging and cleaning the hole the cleaning device 20is lowered into the hole with the arcuate sections 23 and 24 disposed oneither side of the top portion of the pipe 116. The arcuate sections 23and 24 are normally biased toward a closed or radially inward positionby helical spring 32 acting against nut and bolt 31. The arcuatesections 23 and 24 are extended by forcing the rollers 30 against thepipe section in a downward direction so the sections expand and thencontract and snap into place about the pipe.

The operator uses the handle 20 to maneuver the sections 23 and 24carrying noule33 with its opening 34. The arcuate sections 23 and 24 arerotated around the pipe into positions shown in FIGURE 5 and FIGURE 6 asthe blast is applied to the face of the bell as shown in FIGURE 2, or tothe spigot as shown in FIGURE 5. The shoulder 41 is provided with radialstuds 49 so that the nozzle may be rotated with a suitable forked rodapplied from above ground for adjustment of the direction of the blast..It is also relatively easyfto remove the cleaning device from the holeto rotate the nozzle 33 to get a selected-direction for the blast. Thecleaning device is rotated through the entire 360 circumference of thepipe by alternatively flopping the handle so that the U bend 28 is onthe one side of the pipe during the 180 of rotation as shown in FIGURE5, and then on the other side of the pipe through the remaining 180 ofrotation as shown in FIGURE 6. The handle rotates about the pivot 27during this flopping from one side to the other.

After the bell and spigot have been sand-blasted, the cleaning'meohanismis removed by pulling upwardly on the handle. A suction cleaner 119 isthen introduced into hole 115, as shown in FIGURE 15, and the grit orblast material is removed from the hole and from the vicinity of thejoint.

The mold device of. the invention is then introduced into the hole bythe following method. The cable 87 which forms the loop around saddle 98is removed and dropped into the hole on one side of the pipe while therest of the device is above the hole. mechanism, such as a pole with ahook on the end, is introduced on the opposite side of the pipe and theloop of cable 87 in the hole is fished under the main. Also, a block ofmagnetic material may be attached to the bight of the cable and asuitable fishing magnet can then be used to pull the cable through underthe main. T-he mold and frame are then lowered by means of handle 92.The mold and frame are in an open position, as shown in FIGURE 8, byvirtue of the resilience of the flexible mold which has a tendency tocircumferentially separate at faces 102 and 103 so that a gap existsbetween these faces as shown in FIGURE 8.

The mold and frame are lowered completely over the main as shown inFIGURE 9. This is conveniently accomplished by alternatively pushingdown on the handle 92 and pulling up on the cable which has been passedunder the pipe. The bight of the cable 87 is then looped over the saddle98. The guides 90 and on the terminal segment 88 guide the terminalsegment 101 of the frame into position as tension is applied to cable 87by saddle 98 so that the cable is drawn upwardly along the handle byoperation of the jack mechanism.

A linear force on cable 87 along handle 92 is converted to a tangentialforce at 117 (FIGURE 9) so that a radially inward force is created bythe cable at each segment of the mold frame. Since separate cableportions extend circumferentially along longitudinal segments 70 and 71,separate radial forces are exerted upon these segments, Each segment 71acts independently against mold section 55 to contract and retain themold against the outer circumferential face of the bell end. Eachsegment 70 also acts independently against mold section 52 to contractand retain the mold against the spigot.

By virtue of these articulated segments compensation is automaticallymade for any variance of the bell or spigot from true roundness and forany'variance of any fixed relationship between the bell and the spigotlongitudinally, axially or otherwise. i

A suitable sealing compound is introduced through open valve 114 andtube under pressure and through inlet opening 107 into mold cavity 65.Gases from the cavity escape through outlet opening 106 and outlet tube108 through open valve 112 to atmosphere. As soon as the sealing fluidemerges through outlet open- 106 and is seen in transparent outlet tube108, valve 112 is closed and the pressure is increased until it isslightly in excess of the pressure of the gas in the main, so that thesealant is forced into leak-passages and escape of gas is prevented andthus a tendency to form gas bubbles in the plastic sealing compound willnot exist. The pressure of the air above the sealant in outlet tube 108is read on gage 113. .The pressure on said material is maintained untilit has hardened. As the sealant cures it may have a tendency to shrinkwhich together with the expansion of the plastic tubes 108 and 110 wouldcause a drop in pressure as registered on gage 113. Fitting A suitablefishing -104 which secures the cable under tension to the handle bytightening bolt 105. This allows force to be released on the cable atsaddle 98 without releasing the tangential force being applied to themold frame. The jack mechanism and the outmost sections of the handleare removed and the cable loop is permitted to drop into the hole asbest seen in FIGURE 17. In this position, the entire mold mechanism andthe lower portion of the handle is below the surface of the pavement anda hole cover 118 is placed over the hole,'secured in place if desired.In this condition trafiic, both vehicular and pedestrain, can move overthe covered hole in safety.

After the sealing material sets in the cavity 64, for example, from lessthan one hour to about twelve hours, depending upon the sealant used,tension on cable 87 is released and the cable loop is allowed to dropinto the hole. The resilience of the mold causes the mold and frame toopen as shown in FIGURE 8, especially if a suitable parting compound hasbeen employed to permit separation from the sealing material, and themold and frame are removed from the hole by use of the handle 92. Thefill and vent tubes 107 and 106 and the associated plastic tubing arereplaced with new tubes and the mold recoated with the release agent andthe apparatus is then ready to reuse. The advantage of using sealantswith shorter curing time is that more joints can be rescaled per daywith a single sealing apparatus.

In view of our invention and disclosure, variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled in the art, to obtain all or part of the benefits of ourinvention without copying the method and structure shown, and we,therefore, claim all such insofar as they fall within the reasonablespirit and scope of our claims.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent is:

l. A method of sealing an area of an underground conduit containingfluid under superatmospheric pressure, which comprises the steps ofexcavating a narrow shaft above an area of the conduit to be sealed,lowering into the excavation and disposing in open position partiallysurrounding the conduit a split elastomeric mold, closing said moldabout the area of the conduit to be sealed, applying radially inwardforce to the outside of the mold to press said mold into tight radialengagement with the conduit leaving a completely annular space betweensaid mold and the area of the conduit to be sealed, introducing ahardenable sealing material into the space between the mold and the areaof the conduit to be sealed under external pressure in excess of thepressure in the conduit and at the same time pushing out the gases insaid space to the atmosphere ahead of the sealing material, and when thesealant fills the mold maintaining the tight engagement of said moldwith said conduit and the pressure on said material in excess of thepressure in the conduit until the material has hardened.

-2. A method of claim 1, in which said radially inward force is producedby applying tension on flexible circumferential elements surroundingsaid mold from above the surface of the excavation.

3. A method of claim 1, in which said conduit is a gas main, and inwhich leakage occurs from the gas main at said area, through an aperturein the conduit wall in the area, which further comprises introducingsaid hardenable sealing material from said space into said aperture,notwithstanding the pressure in the main, thereby sealing said leakage.

hardenable sealing material into the space between the 4. A method ofsealing an area of an underground gagement of said mold with saidconduit and the pres conduit containing fluid under 'superatmosphericpressure on said material in excess of the pressure in the sure, whichcomprises the steps of excavating a narrow conduit until the materialhas hardened. shaft above an area of the conduit to be sealed, lowering5. A mcthcd of claim 4, wherein after said material into the excavationand disposing in open position par- 5 has hardened, the externalpressure on the material is tially surrounding the conduit asplit'elastomeric mold relieved, the circumferential force is removedfrom the within a coextensive longitudinally and transversely fr me, thmold is r leased from engagement with the articulated segmentedreinforcing frame having longi conduit, and the mold and frame areopened and removed tudinally separate groups of segments, closing saidmold from the excavation. and said frame about the area of the conduitto be sealed, 10

applying circumferentail tensile forces on the respective ReferencesCited by the Examm" longitudinal groups of segments of said frame topress UNITED STATES PATENTS said mold into tight radial engagement withthe conduit 2 055 885 9/1936 Weston 25 127 XR leaving a, completelyannular space between said mold 2163261 6/1939 Norton a n and the areaof the conduit to be sealed, introducing a 15 2:2 g:0 9 7 941 Evans 5127 mold and the area of the conduit to be sealed under ex- FOREIGNPArlrENTs ternal pressure in excess of the pressure in the conduit721,664 1/1955 Great Britain.

and at the same time pushing out the gases in -said space; to theatmosphere ahead ofthe sealing material, and 20 ROBERT WHTTE, when thesealant fills the mold maintaining the tight en- J. A. FINLAYSON,Assistant Examiner.

1. A METHOD OF SEALING AN AREA OF AN UNDERGROUND CONDUIT CONTAININGFLUID UNDER SUPERATMOSPHERIC PRESSURE WHICH COMPRISES THE STEPS OFEXCAVATING A NARROW SHAFT ABOVE AN AREA OF THE CONDUIT TO BE SEALED,LOWERING INTO THE EXCAVATION AND DISPOSING IN OPEN POSITION PARTIALLYSURROUNDING THE CONDUIT A SPLIT ELASTOMERIC MOLD, CLOSING SAID MOLDABOUT THE AREA OF THE CONDUIT TO BE SEALED, APPLYING RADIALLY INWARDFORCE TO THE OUTSIDE OF THE MOLD TO PRESS SAID MOLD INTO TIGHT RADIALENGAGEMENT WITH THE CONDUIT LEAVING A COMPLETELY ANNULAR SPACE BETWEENSAID MOLD AND THE AREA OF THE CONDUIT TO BE